import React, { Component,lazy,Suspense} from 'react'
import {NavLink,Route} from "react-router-dom";
// 1.下面这种写法页面挂载时加载所有的组件
// import About from './About';
// import Home from './Home';


import Loading from './Loading'
// 2.路由懒加载,点谁请求谁进而展示谁
const About = lazy(()=> import('./About'))
const Home = lazy(()=> import('./Home'))

export default class Demo extends Component {
  render() {
    return (
      <div>
        <div className="row">
          <div className="col-xs-offset-2 col-xs-8">
            <div className="page-header"><h2>React Router Demo</h2></div>
          </div>
        </div>
        <div className="row">
          <div className="col-xs-2 col-xs-offset-2">
            <div className="list-group">
                <NavLink className="list-group-item" to="/about">About</NavLink>
                <NavLink className="list-group-item" to="/home">Home</NavLink>
            </div>
          </div>
          <div className="col-xs-6">
            <div className="panel">
              <div className="panel-body">
                  <Suspense fallback={<Loading/>}>
                    <Route path='/about' component={About}/>
                    <Route path='/home' component={Home}/>
                  </Suspense>
              </div>
            </div>
          </div>
        </div>
      </div>
    )
  }
}
